Process for securing a shrinkable fastener to a container



Dec. 10, 1963 w. c. KIRKPATRICK ETAL ,4

PROCESS FOR SECURING A SHRINKABLE FASTENER TO A CONTAINER 2 Sheets-Sheet1 Filed Dec. 3, 1959 INVENTORS w m K m m RN 5 m AS w w k RR. Jr mmo /M%H w INE LHB YOO WIVR 1963 w. c. KIRKPATRICK ETAL I 3,113,408

PROCESS FOR SECURING A SHRINKABLE FASTENER TO A CONTAINER Filed Dec. 3,1959 2 Sheets-Sheet 2 WYLIE C. KIRKPATRICK JORHN W.HARRISON ROBERTD.LOWRY ATTORNEYS INVENTORLS United States Patent 3,113,4tl8 PRUEESS FGRSEQURIING A SHRHNKARLE FASTENER TG A CGN'IAINER Wylie C. Kirkpatrick,Wayland, and John W. Harrison and Robert D. Lowry, Winchester, Mass,assignors to W. R. Grace 8: (30., Cambridge, Mass a corporation ofConnecticut Filed Dec. 3, 1959, Ser. No. 857,613 8 Claims. (Cl. 533tThis invention relates to a fastening member useful for binding orsecuring parts or articles together. More particularly this inventionprovides a fastening member formed of a heat shrinkable polymer such asheat shrinkable polyethylene, vinylidene chloride (saran), polypropyleneor polyethylene terephthalate (Mylar). Specifically, the inventionprovides as a fastening member a rivet or filament for joining partstogether, said member being formed of a heat shrinkable,mono-directionally oriented irradiated polyethylene polymer.

By the heat shrinking process, the polymer shrinks longitudinally whileconcurrently expanding laterally. In a preferred embodiment of theinvention, it is possible to expand a fastening member, such as a rivet,from a loose internal fit to a tight secure internal fit, by utilizing asufiicient amount of the shrinkable material.

An object of this invention is to provide a new type of a fasteningmember that can be used in any of several modifications hereinafterdescribed.

More particularly, an object of this invention is to provide a fasteningmember formed of a heat shrinkable uni-axially oriented polymer adaptedto substantially shrink along its axis of orientation and expand alongits other axis so that upon the applicationof heat the fastening memberwill shrink along its oriented'axis and expand along its other axis.

FIGURE 1 perspectively shows a partially broken away View of a length ofheat shrinkable, uni-oriented irradiated polyethylene about to be heatedin place to form a rivet;

FIGURE 2 is a sectional view of the solid rivet formed and secured inplace;

FIGURE 3 is a view similar to FIGURE 2 but utilizing a hollow rivet;

FIGURE 4 is yet another modification showing a length of solid rodhaving both ends passing through a backing material thereby forming aloop adapted to fasten articles of merchandise to the board;

FIGURES 5, 6, 7, and 8 are perspective views of a flexible closurehaving its ends constricted by novel fastening members made according tothis invention; FIGURES 5 and 6 illustrate pressure sensitive tape asthe fastening means and FIGURES 7 and 8 illustrate a mono-filament formof said polymer;

FIGURES 9 and 10 are perspective views of another adaptation comprisinga rope end being Whipped by a mono-filament form of said polymer;

FIGURES l1 and 12 show a display card having the articles fastenedaccording to the novel features of this invention; FIGURE 11 being aperspective view of the fastening member in place before being heatedand FIG- URE 12 being a sectional view of the same display after theinsertion of articles and the application of heat; and

FIGURE 13 shows a modification of a display card having a band aroundthe display article and the card.

While the invention is susceptible of assuming many forms andmodifications as illustrated in the several drawings the discussioninitially will relate more particularly to the fastening member shown byFIGURES 1 through 4 such as a rivet where the effect of the longitudinalshrinking and lateral expansion leads to unique results.

Thus by utilizing the longitudinal shrink and lateral swelling orexpansion ability of uni-oriented irradiated polyethylene either as arod (FIGURE 2) or tube there can be formed a rivet. In some instances aplurality of filaments can be employed rather than just one.

The parts to be riveted l2 and 16, e.g., two pieces of wallboard, metalsheeting, glass fabric, polyvinyl resins or wooden blanks, etc., arebrought together as shown in FIGURE 1 and holes are drilled through allparts where desired. The solid rod 10 cut to a predetermined lengthsufiicient to have both ends project beyond the parts being joined isthen inserted into these aligned holes and while there positioned, issubjected to heat by any suitable source indicated by blower 14. Thefilament rod should have a diameter only slightly smaller than thediameter of the holes. The shrinking takes place in the direction of theorientation, in the case of rivets being longitudinally, whileconcurrently the lateral expansion is occurring. As a consequence beadsor heads 11, FIGURE 2, are formed at both ends of the rivet. These beadsabut against the shoulders of the aligned holes, since the shrinkingoccurs on the longitudinal axis of the stem of the rivet. The stem 10,of course, expands laterally to press firmly against the internal sidesof the drilled holes. In FIG- URE 3 the solid rivet 10 of FIGURE 2 isreplaced by hollow rivet 13 and heads 15 are formed upon heating.

Whereas FIGURES 1, 2 and 3 all show a straight filament rod 10 haivngits ends 11 projecting beyond the parts, 12 and 16, being joined. FIGURE4 illustrates a modification where one of the ends is extended to asulficient length such that it can be adapted to reenter the boardthrough a second hole and be securely fastened in a similar way, i.e.,expanded by heating as at 19. There is thus formed a loop 17 which canbe subsequently shrunk by additional heat to fasten an article ofmerchandise, etc., to the board.

. Features common to each of these modifications are the ease andinexpensiveness with which the process is carried on and the securebinding power that can thereby be attained.

The polymers best adapted for the invention are monodirectionallystretched irradiated polyethylene and monodirectionally stretchedpolypropylene.

The application of this principle of longitudinal shrinking and lateralexpansion is equally useful as a means for fastening or securing theends of various plastic closures or flexible bags, for example, as seenin FIGURES 5, 6, 7 and 8.

In FIGURES 5 and 6 the polymer is utilized in the form of conventionalpressure sensitive tape 24 and in FIGURES 7 and 8 as mono-filament 26adapted to be wrapped about the gathered end 22. Both modificationsdepend for the constricting means on the high shrink energy released bythe uni-axially irradiated polyethylene polymer at shrink temperatures.The open end of bag 20, can be gathered to form a closure or optionallytwisted as at 22 and then wrapped with the polymer and heat shrunk withthe result that the closure becomes a good moisture and/or gas barrier.In place of a bag a tube can be employed and both ends closed in themanner indicated.

The end of an inflated bag 20' was twisted 22 as though for theconventional application of a clip.

About said twisted portion there are wrapped about three moderatelytightly applied turns of pressurized sensitive tape. The tape can easilybe made by knife coating mono-directionally oriented irradiatedpolyethylene film about 3 mils thick with pressure sensitive siliconeadhesive (a polydimethyl silicone).

Inplace of the tape, a monofilament can be substituted with even betterresults. FIGURES 7 and 8 illustrate the use of such a filament. The bag20- has been filled and 3 its ends twisted 22 in a manner exactly as inFIGURES 5 and 6. About turns of a monofila-ment 26 are applied as thoughwhipping rope. A knot should be tied in order for the monofilament toexert a force on the closure when shrunk.

Subsequently upon heating to about 205 F. the polyimer shrinkslongitudinally and expands laterally whereby the closure when tested bysqueezing the inflated portion is found to be very adequately sealed.

FIGURES 9 and 10 illustrate another application of this invention. Thehigh shrink energy of a monofilament as depicted in RIGURES 7 and 8 isused to form an unusually tight aniti-fraying binding one the end of arope. The monofilament is applied using the common technique forwhipping wherein the ends are locked under the wrapping. A similarprocess called serving in which along segment of rope is similarlybound, with or without previous worming and parceling can also beemployed.

Specifically, the rope end 30 is Whipped and the Whipping subsequentlyheat shrunk, using a monofilament of irradiated polyethylene 32 whichhad been mechanically elongated by stretching.

Another novel feature of this application is that the filament ends canbe tied outside the wrapping, and by applying heat so that the looseends fro-m the knot shrink first, the knot 34 will not subsequentlyuntie as is common in plastic yarns.

A means of affixing merchandise to display cards is illustrated inFIGURES 11 and 12, in which a tape loop 42 is preamxed to the card andmade large enough for easy insertion of the merchandise and issubsequently shrunk to tightly lock the merchandise to the card.Obviously this method can be used to fasten either single or multiplearticles to the card in a similar manner. An instance of at least twoarticles is illustrated in FIGURE 12. Two fuses 48 are there shown beingheld in place by a film longitudinally shrunken 42 about the base bead50 of each fuse.

in detail, a display card such as a blank of cardboard iiiis perforatedWith two parallel slots 46 to permit the ends 44, '45, of a loop of tape42 to enter and be fastened in the underside by a convenient means, suchas a strip of pressure sensitive tape or a staple (not shown). The loop42 was left sulficiently large for easy insertion of the merchandise tobe displayed as in the case of FIGURE 12, two household fuses 48.

The tape 42. had to be wide enough to overlap the beadedges 50 of thebase of the two fuses so that after the application of heat the banddrew down and conformed to the bead shape, tightening the fuses to thecard, and locking them in place by reason of the form fit over thebeads.

The tape used can, of course, be fastened to the card in alternate wayssuch as by staples, heat sealing, adhesives, etc., or can be a bandaround both the object displayed and the card. In FIGURE 13 a band isused around both the object displayed and the card. A pair of notches 51are made in opposite edges of the card and the portions 52 between thenotches are folded at right angles to the card face. This results in astrengthening of the card and provides a recess to hold the band 53 inplace.

The uni-axial stretching or orientation can be accomplished in anymanner known to the ant, e.g., as shown in Rainer Patent 2,877,500. Byuni-axial orientation, the molecules are assmbled in columns facing inthe direction of stretch, e.g., lateral or longitudinal.

The degree of stretching should be suflicient to provide the minimumconstrictive force necessary for any given application to which it is tobe put. For example, it can be heated and stretched 200%, 300%, or 500%or 900% or even more. The irradiation can be to a dosage of 2 to 100megarad, preferably 6 to 20 megarad. in the examples there was employedAlathon 14 (polyethylene) irradiated at a dosage of 12 rnegarads withhigh energy electrons.

As a matter of fact, the transparent polyethylene derived by thatprocess including the uni-axial stretching step provided thereby hasbeen found of excellent quality when used in this invention.

The desirability of having the polymer being transparent will vary withthe applications described herein as Well as other applicationssuggested thereby. This charaoteristic of the polymer, however, isincidental to the capability of shrinking longitudinally and expandinglaterally.

it is to be understood that while several illustrations of the novelfastening member have been described, this application is expresslyintended to cover all modifications and changes which come within thespirit of this invention and the scope of the appended claims.

What is claimed is:

1. The process of securely binding a container comprising the steps of:wrapping about an end of said container a length of heat shrinkableuni-axially oriented polymer; heating said polymer to effect concurrentshrinkage along its axis of orientation and expansion along its otheraxis to thereby seal said end.

2. A process for aifixing merchandise to a support comprising placingthe merchandise on the support, affixing a tape loop of a heatshrinkable uni-axially oriented polymer to said support around saidmerchandise and then heat shrinking said polymer to tightly lock themerchandise to said support.

3. A process of securely binding a bag comprising the steps of gatheringthe open end of the bag to form a closure, Wrapping about said gatheredend a length of heat shrinkable uniaxially oriented polymer, heatingsaid polymer to effect concurrent shrinkage along its axis oforientation and expansion along its other axis to thereby constrict andseal said end.

4. A process according to claim 3 wherein said polyrner is uniaxiallyoriented, irradiated polyethylene.

5. A process according to claim 3 wherein said uniaxially orientedpolymer is polypropylene.

6. A process according to claim 2 wherein the polymer is uniaxiallyoriented, irradiated polyethylene.

7. A process according to claim 2 wherein the uni axially orientedpolymer is polypropylene.

8. A process according to claim 1 wherein the polymer is uniaxiallyoriented, irradiated polyethylene.

References Cited in the file of this patent UNITED STATES PATENTS2,458,152 Eakins Jan. 4, 1949 2,510,693 Green June 6, 1950 2,788,625Larsen Apr. 16, 1957 2,890,552 Henderson June 16, 1959 2,941,911 Kumnicket a1 June 21, 1960 2,970,416 Kreuger Feb. 7, 1961 2,974,559 Coggi Mar.14, 1961 OTHER REFERENCES Shrink-Tight Polyethylene, an article in theMarch 1955 issue of Modern Packaging (see page 100). (Copy in Div. 67.)

How Radiation Affects Long-Chain Polymers, an article in the June 1954issue of Nucleonics (see page 20). (Copy in Div. 67.)

1. THE PROCESS OF SECURELY BINDING A CONTAINER COMPRISING THE STEPS OF:WRAPPING ABOUT AN END OF SAID CONTAINER A LENGTH OF HEAT SHRINKABLEUNI-AXIALLY ORIENTED POLYMER; HEATING SAID POLYMER TO EFFECT CONCURRENTSHRINKAGE ALONG ITS AXIS OF ORIENTATION AND EXPANSION ALONG ITS OTHERAXIS TO THEREBY SEAL SAID END.